The present invention relates to devices and methods for detecting a vital parameter and, for example, to the control of optoelectronic sensor arrangements used for this purpose.
The methods of optical plethysmography and pulse oxymetry are methods for a none invasive determination of vital parameters of a living being, e.g., of the pulse rate, the pulse rate variability and the arterial oxygen saturation, by measuring a light absorption or a light remission in the tissue of the living being.
Typically, the oxygen saturation values or SpO2 values are tapped via an optical sensor at the finger, toe or earlobe, wherein measuring is executed by means of a clip sensor or an adhesive sensor.
The application of optical plethysmography and pulse oxymetry for detecting such vital parameters may, however, also be executed under automobile conditions, i.e., in a automobile or a vehicle, for example by integrating the optical sensors into operating elements of the vehicle. This enables a detection of the vital parameters with little adverse effects on the driver. One possible implementation is the integration of the optical sensor into a gear level knob of the vehicle.
The sensors typically consist of two light sources, e.g., a red diode and an infrared diode and a photo sensor or photodiode. As soon as the optical sensor is switched on, the two diodes light up. The infrared diode radiates in the non visible range of the electromagnetic spectrum, in contrast to that the red diode radiates in the visible range of the electromagnetic spectrum. On the one hand this may distract the driver and on the other hand it may negatively affect the light design of the interior of the vehicle, e.g., when the predominant color is green or blue.